Continue ongoing studies designed to evaluate in non-human primates the carcinogenicity of various chemicals. Generally, the contractor will maintain a breeding colony and administer chemical carcinogens and antitumor agents to the colony. Various physical and chemical parameters will then be monitored to evaluate the general health status and detecting tumorigenesis. Also, the contractor will obtain model tumor systems to ascertain the usefulness of anticancer agents before clinical trials and evaluate the long-term effects of clinically useful antineoplastic and immunosuppressive agents.